June 15, 2011

Scientists Find Magnetic Rope Source For Solar Storms

Scientists at George Mason University discovered that a phenomenon called a giant magnetic rope is the source for solar storms.

The researchers made the discovery by using images from the NASA Solar Dynamic Observatory (SDO) spacecraft.

Scientists had previously been unable to prove that the magnetic rope was the cause of solar storms.

However, using images taken by the Atmospheric Imaging Assembly (AIA) telescope aboard the SDO, the team was able to pinpoint an area of the sun where a magnetic rope was forming. The AIA telescope suite is able to capture images of the Sun every 10 seconds, 24 hours a day.

"The magnetic rope triggers a solar eruption. Scientists have been debating whether or not this magnetic rope exists before a solar eruption. I believe that the result of this excellent observation helps finally solve this controversial issue," Jie Zhang, associate professor at George Mason University, said in a statement.

A solar storm is a violent eruption from the sun that sends billions of tons of charge material, known as plasma, into space at a speed of over 1 million miles per hour. The plasma carries a strong magnetic field with it.

As the magnetized cloud reaches Earth one to three days later, a huge amount of energy is deposited into the magnetosphere of the Earth.

A solar storm can have harmful effects on a variety of technological systems, including satellite operation, communication and navigation and electric power grids.

The researchers' discovery will help in giving early warning about solar storms and help to minimize the damage done by space weather on Earth.

"Understanding the eruption process of these storms will definitely help us better predict them," Zhang said in a statement. "We cannot prevent solar storms, just like we cannot prevent earthquakes or volcanoes. But the development of prediction capacity can help mitigate adverse effects. For instance, satellite operators can power-down key systems to prevent the possible damage to the systems."

It is theorized that magnetic fields in the Sun play an essential role in storing energy and powering solar storms. However, the exact form magnetic field lines take prior to the eruption are highly controversial.

Scientists believe the magnetic rope was the phenomenon that powered the eruption. A magnetic rope contains many magnetic field lines wrapping around a center axis and possibly twisting around each other.

The researchers found that before an eruption, there is a long and low-lying channel running through the entire active region, which heats to a temperature as high as 10 million degrees.

When it reaches a critical point, it starts to erupt quickly. It is a feature distinctly different from the surrounding magnetic field lines. Scientists believe this hot channel is the magnetic rope they have been looking for.

The results were reported at the American Astronomical Society Solar Physics Division Meeting, held in Las Cruces, New Mexico on June 12 - 16, 2011.

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Image 1: Sun's image taken at 03:41 UT on March 8, 2011, showing numerous loops of magnetic fields emanating from multiple island-like active regions across the surface of the Sun. The white box encloses the particular active region where the giant magnetic rope was discovered. The image, taken by the Atmospheric Imaging Assembly (AIA) telescope on board SDO at the Extreme Ultraviolet wavelength of 171 Angstrom, maps the highly-charge corona gas material at temperature about 1 million degree Celsius. ). More details can be seen in video 1. (Credit: NASA and GMU)

Image 2: On the left, SDO AIA image at the wavelength of 131 Angstrom observing the Sun's atmosphere at a temperature of about ten million degree. The magnetic rope is seen as the thick looped structure extending above the edge of the Sun. On the right, SDO AIA image at wavelength 171 Angstrom observing the corona at a temperature of about one million degree, showing surrounding cool magnetic field lines are pushed away by the intruding magnetic rope seen on the left. Both images are taken almost simultaneously (within three seconds of each other) at 03:41 UT. More details can be seen in video 2. (Credit: NASA and GMU).